Azure AZ-204 App Insights Guide

This lesson covers the monitoring lane Microsoft explicitly calls out in the current skills measured. AZ-204 expects you to know how metrics, logs, traces, availability tests, and alerts help you prove what is broken before you change the application.

Availability test: Synthetic check that verifies whether an application endpoint stays reachable and responsive.

Trace: Request-level execution history that helps explain where time was spent or where failure occurred.

What Microsoft is really testing here

AZ-204 is checking whether you can pick the right signal before you start changing code:

• metrics for trends and threshold breaches
• logs for concrete event records
• traces for request path and dependency timing
• synthetic tests for endpoint reachability
• alerts for turning those signals into action

Fast observability chooser

Metrics versus logs versus traces

    flowchart LR
	  A["Something looks wrong in production"] --> B{"What do you need first?"}
	  B -->|Trend or threshold| C["Metrics"]
	  B -->|Concrete event records| D["Logs"]
	  B -->|Request path and dependency timing| E["Traces"]
	  B -->|Outside-in endpoint reachability| F["Availability test"]
	  C --> G["Alert rule if action is needed"]
	  D --> G
	  E --> G
	  F --> G

Common traps

Harder scenario question

An application team sees intermittent failures. They need to know whether the public endpoint is reachable, whether latency is trending up over time, and where time is spent when a request calls downstream services.

The strongest first reading is:

1. use availability tests for reachability, metrics for latency trend, and traces for request-path timing
2. use logs only because they contain all signals
3. use SAS because the issue is temporary
4. use Key Vault because failures can be secrets-related

Correct answer: 1. The problem explicitly splits into synthetic reachability, trend analysis, and request-flow analysis.

Decision order that usually wins

1. First classify the need as synthetic availability check, request-path diagnosis, or threshold-based operational alerting.
2. If the app needs a scheduled outside-in endpoint check, think Application Insights availability test.
3. If the question is about where execution time or failure occurred through the app path, think trace data.
4. If the question is about crossing a configured latency or failure threshold, think metrics and alert rules.
5. Keep logs, traces, and metrics separate because the exam uses them as confusion pairs.

Quiz